1. Field of the Invention
This invention relates to a two-cycle internal combustion engine.
2. The Prior Art
In a two-cycle internal combustion engine, a piston is arranged in a cylinder in such a manner that it can perform a reciprocating movement therein. This piston is connected with a crankshaft through the intermediary of a connecting rod. The movement of the piston toward top dead center introduces a air-fuel mixture into a pre-compression chamber (crankcase) through an intake port formed in the cylinder. The air-fuel mixture thus has been previously pressurized by the movement of the piston toward bottom dead center. The pressurized air-fuel mixture is supplied to a combustion chamber of the cylinder through scavenging channels. One end of the connecting rod is normally pivoted, through the intermediary of a bearing portion, to a piston pin mounted on the piston. In particular, in the case of a two-cycle internal combustion engine whose cylinder is so positioned in use that it extends upwards from the pre-compression chamber, there is some difficulty in effecting lubrication in the bearing provided between the connecting rod and the piston pin. Therefore, it is necessary to provide a needle roller or the like in the bearing portion between the connecting rod and the piston pin. Moreover, such members are have poor durability, and the load applied to them in use has to be restricted.